Has animations showing the movement of volcanic ash after a volcano puffs out the ash. (Has Mt. St. Helen's half way down the page)
http://puff.images.alaska.edu/Google_Earth2.shtml
Information on the Redoudt 1989 eruption - an airplane flew into the ash cloud in/near Alaska; all 4 engines stopped. Had to descend, where engines restarted, and made an emergency landing in Alaska. http://puff.images.alaska.edu/Redoubt_webpage/Puff_redoubt_ash.shtml